The present invention relates to a circuit card retention mechanism, and more particularly, to a retention mechanism that secures a printed circuit card edge connector to an electrical connector mounted on a main circuit board.
Today, printed circuit cards are used in many electronic devices, such as computers and telecommunications equipment. In these devices, printed circuit cards are often electrically connected to a main circuit board using connectors that extend from the printed circuit card that mate with connectors located on the main circuit board.
In conventional personal computers (PC""s), for example, the main circuit board is generally referred to as the motherboard. The electrical connector located on the motherboard in a PC is generally referred to as a card slot and can receive a variety of printed circuit cards that support, among other things, video displays, serial interface ports, parallel interface ports, computer memory (RAM) and additional data storage. Many of the printed circuit cards provide input and output connections disposed generally on one or more sides of the printed circuit card for connection to external equipment as well as other components internal to the electronic device. Indicator lamps and displays are often disposed on an external face of the printed circuit card to indicate equipment status.
In PC equipment, the printed circuit card electrically mates with the main circuit board when it is installed in a card slot with the printed circuit card connector mated to the main circuit board connector. Printed circuit cards are usually held in place with a fastening means, such as a screw, installed at one end of the card. Even with this fastening means, printed circuit cards are very sensitive to motion and a small degree of motion can dislodge a card and result in equipment malfunction.
Although a manufacturer tests the equipment prior to shipping, cards may partially dislodge during shipping and handling and result in subsequent malfunction. The loss of electrical contact that results from partially dislodged cards is often difficult to diagnose because only some of the electrical contacts between the printed circuit card and the main circuit board are lost. Thus, connection between the circuit card and the main circuit board is not completely lost but only impaired, which can be difficult to diagnose. This often leads to calls from dissatisfied customers requesting manufacturer assistance in debugging equipment failures. This extended involvement with the customer increases manufacturer costs and decreases customer confidence in the underlying equipment.
Several patents have issued in an attempt to cope with some of these problems. For example, U.S. Pat. No. 5,650,917, issued to Hsu on Jul. 22, 1997, relates to a Central Processing Unit (CPU) mounting structure that includes a U-shaped mounting frame mounted on an electrical connector that receives a CPU card. The CPU card is held in the U-shaped mounting frame by two holding down devices, i.e., screws. The mounting structure, which is intended for use with CPUs, makes unusable a sizeable amount of space on the circuit board as the U-shaped structure extends on three sides of the board. The U-shaped structure also does not allow interface access to the printed circuit card on the sides.
Another example, U.S. Pat. No. 4,826,447, issued to Forker et al. on May 2, 1989, relates to a retainer for locking a printed circuit board with an edge connector that is directly soldered to the conductive paths on a second circuit board. The circuit board is permanently connected to the connector and is removable only after disengaging the retainer and de-soldering the electrical connections to the second circuit board. The retainer, which does not allow interface access to the printed circuit card on the sides, requires a large surface area of potentially usable circuit board space.
Thus, as can be seen, there is a need for a sturdy and reliable printed circuit card retention mechanism that is easy to engage and disengage and does not require de-soldering of connections. There is a further need for a printed circuit card retention mechanism that does not damage the printed circuit card when the retention mechanism is engaged and disengaged. There is yet a further need for a printed circuit card retention mechanism that occupies a minimum of the usable surface area on the printed circuit card and allows for access to connectors on both sides of the printed circuit card.
Accordingly, the present invention is directed to a circuit card retention mechanism having a base which fits over an end of an electrical connector of a motherboard and an extension piece which is connected to the base and which secures to a circuit card. The base is constructed comprising a pair of lateral wall pieces diametrically opposed and facing one another, a crosspiece which integrally connects the pair of lateral wall pieces at an end, and a support piece integrally connected to and extending outwardly from a bottom portion of the crosspiece. The extension piece can take the form of either a tie-wrap or a retainer clip.
Dependant upon what form the extension piece takes, the base can also further comprise at least one cutout in each one of the pair of lateral wall pieces and at least one pointed bite positioned in each one of the at least one cutouts and which is flexibly biased towards the electrical connector, or can secure to the motherboard itself
The present invention and its features and advantages will become more apparent from the following detailed description with reference to the accompanying drawings.